Shear Velocity Evidence of Upper Crustal Magma Storage Beneath Valles Caldera

Justin Wilgus*, Brandon Schmandt, Ross Maguire, Chengxin Jiang, Julien Chaput

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

7 Citations (Scopus)

Abstract

Valles Caldera was formed by large rhyolitic eruptions at ∼1.6 and 1.23 Ma and it hosts post-caldera rhyolitic deposits as young as ∼69 ka, but the contemporary state of the magmatic system is unclear. Local seismicity beneath Valles Caldera is rare and shear-velocity (Vs) structure has not been previously imaged. Here, we present the first local Vs tomography beneath Valles Caldera using ambient noise Rayleigh dispersion from a ∼71 km transect of nodal seismographs with mean spacing of ∼750 m. An ∼6 km wide low-Vs anomaly (Vs < 2.1 km/s) is located at ∼3–10 km depth within the 1.23 Ma caldera's ring fracture. Assuming magma in textural equilibrium, the new tomography suggests that melt fractions up to ∼17%–22% may be present within the upper crustal depth range where previously erupted rhyolites were stored.

Original languageEnglish
Article numbere2022GL101520
JournalGeophysical Research Letters
Volume50
Issue number5
DOIs
Publication statusPublished - 16 Mar 2023

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